Name
NV_texture_multisample
Name Strings
NV_texture_multisample
Contact
Jeff Bolz, NVIDIA Corporation (jbolz 'at' nvidia.com)
Status
Shipping on NVIDIA GPUs (GeForce 8 and up) since Release 190.
Version
Last Modified Date: 09/10/09
Revision: 2
Number
403
Dependencies
OpenGL 2.0 is required.
This extension is written against the OpenGL 3.1 specification and the
NV_gpu_program4 extension.
ARB_texture_multisample is required.
This extension interacts with NV_explicit_multisample.
This extension interacts with NV_framebuffer_multisample_coverage.
This extension interacts with EXT_direct_state_access.
Overview
This specification extends NV_gpu_program4 to support per-sample fetching
from multisample textures described in ARB_texture_multisample.
Specifically, it adds:
* The TXFMS sample fetch instruction.
* Texture targets corresponding to the multisample textures added by
ARB_texture_multisample.
* A program option to enable these features.
This specification also extends the ARB_texture_multisample extension
by adding support for EXT_direct_state_access and VCAA multisample
coverage with seperate and parameters.
New Procedures and Functions
void TexImage2DMultisampleCoverageNV(enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TexImage3DMultisampleCoverageNV(enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
void TextureImage2DMultisampleNV(uint texture, enum target,
sizei samples, int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TextureImage3DMultisampleNV(uint texture, enum target,
sizei samples, int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
void TextureImage2DMultisampleCoverageNV(uint texture, enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TextureImage3DMultisampleCoverageNV(uint texture, enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
New Tokens
Accepted by the parameter of GetTexLevelParameter:
TEXTURE_COVERAGE_SAMPLES_NV 0x9045
TEXTURE_COLOR_SAMPLES_NV 0x9046
Additions to Chapter 2 of the OpenGL 3.1 Specification (OpenGL Operation)
Modify Section 2.X.2, Program Grammar
If a program specifies the NV_texture_multisample program option, add to
existing grammar rules if not already present:
::= "2DMS"
| "ARRAY2DMS"
::= "TXFMS"
Add to section 2.X.4.4, Program Texture Access
Add row to table X.17
coordinates used
texTarget Texture Type s t r layer shadow
---------------- --------------------- ----- ----- ------
2DMS TEXTURE_2D_MULTISAMPLE
ARRAY2DMS TEXTURE_2D_MULTISAMPLE_ARRAY
Add row to table X.18
coordinates used
texTarget supported i j k layer lod
---------------- --------- ----- ----- ---
2DMS no - - - - -
ARRAY2DMS no - - - - -
Replace or add language explaining TexelFetchMultisample after the
discussion of TexelFetch
The TXFMS instruction provides the ability to extract a single sample from
a specified renderbuffer, two-dimensional multisample, or two-dimensional
multisample array texture image using the function:
result_t_vec TexelFetchMultisample(int_vec coord, int_vec offset);
The extracted texel is converted to an (R,G,B,A) vector according to Table
3.20. The result vector is interpreted as floating-point, signed integer,
or unsigned integer, according to the data type modifier of the
instruction. If the internal format of the texture is not compatible with
the instruction's data type modifier, the extracted texel value is
undefined.
is a four-component signed integer vector used to identify the
single sample accessed. For the 2DMS and RENDERBUFFER targets, the x and y
components are used to select the pixel and the w component is used to
select the sample. For the ARRAY2DMS target, the x, y, and z components are
used to select the texel and the w component is used to select the sample.
All of the restrictions of TexelFetch apply to TexelFetchMultisample, with
the additional requirement that it must be called on a RENDERBUFFER, 2DMS,
or ARRAY2DMS texture target. If the sample number is greater than or equal
to the value of SAMPLES for the multisample texture, the results are
undefined.
Additions to Chapter 3 of the OpenGL 3.1 Specification (Rasterization)
Add to the end of Section 3.8.4 (Multisample Textures):
The commands
void TexImage2DMultisampleCoverageNV(enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TexImage3DMultisampleCoverageNV(enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
establish the data storage, format, dimensions, and number of samples of a
multisample texture's image where the number of and
can be explicitly specified.
If is zero, then TEXTURE_COVERAGE_SAMPLES_NV
is set to zero. Otherwise represents a request
for a desired minimum number of coverage samples. Since different
implementations may support different coverage sample counts for
multisampled rendering, the actual number of coverage samples
allocated for the renderbuffer image is implementation dependent.
However, the resulting value for TEXTURE_COVERAGE_SAMPLES_NV is
guaranteed to be greater than or equal to and no
more than the next larger coverage sample count supported by the
implementation.
If is zero then TEXTURE_COLOR_SAMPLES_NV is set
to zero. Otherwise, represents a request for a
desired minimum number of colors samples. Since different
implementations may support different color sample counts for
multisampled rendering, the actual number of color samples
allocated for the renderbuffer image is implementation dependent.
Furthermore, a given implementation may support different color
sample counts for each supported coverage sample count. The
resulting value for TEXTURE_COLOR_SAMPLES_NV is determined
after resolving the value for TEXTURE_COVERAGE_SAMPLES_NV.
If the requested color sample count exceeds the maximum number of
color samples supported by the implementation given the value of
TEXTURE_COVERAGE_SAMPLES_NV, the implementation will set
TEXTURE_COLOR_SAMPLES_NV to the highest supported value.
Otherwise, the resulting value for TEXTURE_COLOR_SAMPLES_NV is
guaranteed to be greater than or equal to and no
more than the next larger color sample count supported by the
implementation given the value of TEXTURE_COVERAGE_SAMPLES_NV.
If is greater than , the error
INVALID_VALUE is generated.
If or is greater than
MAX_SAMPLES_EXT, the error INVALID_VALUE is generated.
If is greater than zero, and is
zero, RENDERBUFFER_COLOR_SAMPLES_NV is set to an implementation
dependent value based on RENDERBUFFER_COVERAGE_SAMPLES_NV.
An implementation may only support a subset of the possible
combinations of coverage samples and color samples. Requests for
combinations not supported by the implementation are resolved to
a supported combination using the rules above. The number of
supported combinations is MAX_MULTISAMPLE_COVERAGE_MODES_NV.
MULTISAMPLE_COVERAGE_MODES_NV is an array of
MAX_MULTISAMPLE_COVERAGE_MODES_NV pairs of integers representing
the combinations of coverage samples and color samples supported
by the implementation. The first integer in each pair corresponds
to coverage samples, while the second corresponds to color samples.
(Note: MULTISAMPLE_COVERAGE_MODES_NV and MAX_MULTISAMPLE_COVERAGE_MODES_NV
are specified in the NV_framebuffer_multisample_coverage extension.)
Add to the end of section 3.8.14 (Texture Objects):
The following multisample texture update commands:
void TextureImage2DMultisampleNV(uint texture, enum target,
sizei samples, int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TextureImage3DMultisampleNV(uint texture, enum target,
sizei samples, int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
void TextureImage2DMultisampleCoverageNV(uint texture, enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height,
boolean fixedSampleLocations);
void TextureImage3DMultisampleCoverageNV(uint texture, enum target,
sizei coverageSamples, sizei colorSamples,
int internalFormat,
sizei width, sizei height, sizei depth,
boolean fixedSampleLocations);
operate identically to the corresponding command where "Texture"
is substituted for "Tex" (and extension suffixes are dropped or
updated appropriately) except, rather than updating the current bound
texture for the texture unit indicated by the current active texture
state and the target parameter, these "Texture" commands update the
texture object named by the initial texture parameter. If the
texture parameter is zero, then the target parameter selects the
default texture of the specified target to update. The remaining
parameters following the initial texture parameter for the listed
"Texture" commands match the parameters for the corresponding "Tex"
command and are interpreted as they are for the "Tex" command.
If the texture parameter is for an unused name, the name becomes
used and the named texture object is set to a new state vector,
comprising all the state values listed in section 3.8.11, set
to the same initial values prior to the command's state update.
If the texture parameter is for a used name and that named texture
object has a different target than the specified target parameter,
the INVALID_OPERATION error is generated. One consequence of this
error for commands that accepts TEXTURE_PROXY_* as a valid target
parameter is TEXTURE_PROXY_* target tokens generate errors if used
with a non-zero texture parameter because the target of a non-default
(non-zero) texture object is never a proxy target."
Additions to Chapter 4 of the OpenGL 3.1 Specification (Per-Fragment Operations
and the Frame Buffer)
None.
Additions to Chapter 5 of the OpenGL 3.1 Specification (Special Functions)
None.
Additions to Chapter 6 of the OpenGL 3.1 Specification (State and
State Requests)
None.
Additions to the AGL/GLX/WGL Specifications
None.
New State
(add to table 6.14, Textures (state per texture image p. 252)
Initial
Get Value Type Get Command Value Description Section
-------------------------------- ---- ----------------------------- ------- ------------------- ------------
TEXTURE_COVERAGE_SAMPLES_NV Z+ GetTexLevelParameter 0 Number of coverage 3.8.4
samples per texel
TEXTURE_COLOR_SAMPLES_NV Z+ GetTexLevelParameter 0 Number of color 3.8.4
samples per texel
Interactions with NV_explicit_multisample
If NV_explicit_multisample is not present, the language following the discussion
of Texelfetch in section 2.X.4.4, Program Texture Access will be new and should
omit any mention of sampling from renderbuffers.
Dependencies on EXT_direct_state_access
If EXT_direct_state_access is not supported, remove references to the
TextureImage* commands added by this extension.
Issues
(1) What should this extension be called?
RESOLVED: NV_texture_multisample. It contains the NVIDIA specific portions
of ARB_texture_multisample.
(2) What should the multisample texel fetch opcode be called?
RESOLVED: TEXFMS. It is currently called TXFMS to correspond to the GLSL
builtin, TexelFetchMultisample. It has been suggested that this builtin be
renamed. Even if it is, TEXFMS matches the opcode added via
NV_explicit_multisample. It is better to mismatch GLSL than have two opcodes
for the same operation.
Revision History
Rev. Date Author Changes
---- -------- -------- -----------------------------------------
1 6/23/09 groth Extracted from portions of an earlier version of
ARB_texture_multisample
2 9/10/09 pdaniell Add support for VCAA and DSA